Build your own Function Generator
The AD9837 is a low power, programmable waveform generator IC capable of producing sine, triangular, and square wave outputs.
Below is a circuit design to build your own function generator. The circuit can be connected to a microcontroller through a 3 wire serial interface to set the registers in the waveform generator IC. Package it in a nice enclosure and add some BNC connectors and you have your own Function Generator.
For more detail: Build your own Function Generator